While, as it is, this question seems a bit too do it for me to me, I could see it resulting in a package (or just code) that can draw standard three-stripe (horizontal/vertical) flags with any combination of colors; and potentially a variant with a waving flag, like in the question @Werner pointed to. (And someone might add an animated pstricks version :))
–
doncherryNov 5 '12 at 23:36

So, @Nyang': Welcome to TeX.sx! Please show some attempt you've made in achieving this and specify what you're struggling with. The point of this Q&A site is to solve specific problems, not to have other people do your work.
–
doncherryNov 5 '12 at 23:54

I imagine you want a Scalable Vector Graphic (SVG).Wikimedia Commons has a lot of national flags.
Via Wikipedia:Flag of Kenya I could find a graphic of the flag of Kenya in the the Scalable Vector Graphic (SVG) format.
Download that file and save it locally (.svg).

As pdf(La)TeX/graphicx cannot include files in the SVG format you need to convert it to PDF. The easiest way to do this is probably an online converter (but any converter will do).
As the flag's aspect ratio is 3:2 put a resolution like 300 × 200 in the text boxes that requires the output's size. Download the resulting file and save is as a .pdf file.

In your TeX document and with the help of the graphicx package you can now use \includegraphics[<options>]{filename}.

You most likely need to re-size the resulting image, this can be done with the key-value options width, height, totalheight, keepaspectratio and/or scale (see the graphicx manual for more information).